Problem: $ { \left[\begin{array}{rr}{4} & {0} \\ {-1} & {3} \\ {2} & {-1}\end{array}\right]+\left[\begin{array}{rr}{0} & {3} \\ {1} & {-2} \\ {-1} & {3}\end{array}\right] = {?} } $
To find the sum of two matrices, add the corresponding items between each matrix. ${\left[\begin{array}{rr}{4}+{0} & {0}+{3} \\ {-1}+{1} & {3}+{-2} \\ {2}+{-1} & {-1}+{3}\end{array}\right]}$ Now, simplify: ${\left[\begin{array}{rr}{4} & {3} \\ {0} & {1} \\ {1} & {2}\end{array}\right]}$